On June 6, 2025, AURORA scientists published new research in the peer-reviewed journal Reproductive Toxicology. The study was led by Jeske van Boxel from the Vrije Universiteit Amsterdam, the Netherlands.
The placenta plays a crucial role during pregnancy, but there is a lack of in vitro models to help study how it might be affected by potentially harmful substances. For this latest study, the researchers developed and used an in vitro model that mimics part of the human placenta using two types of human cells: BeWo b30 (a type of placental cell) and HUVEC (Human Umbilical Vein Endothelial Cell; a cell representing the umbilical cord). The model enabled scientists to study whether polystyrene MNPs (PS-MNPs) can pass through the placental barrier and affect these cells.
Van Boxel et al. tested PS particles of different sizes (50 , 200 , and 1000 nanometers) and measured how much of the initial concentration passed these layers after 72 hours . They found that:
- 8.7% of the smallest particles (50 nm) crossed the layers.
- 1.2% of the medium-sized particles (200 nm) crossed the layers.
- None of the largest particles (1000 nm) crossed the layers.
Subsequent microscopy analysis showed that the smaller particles (50 and 200 nm) were detected at both layers (BeWo b30 and HUVEC), while the largest particles (1000 nm) were only detected in the placental layer (BeWo b30).
The researchers then tested whether these particles influenced mitochondrial activity, oxidative stress, and gene expression of several functional markers and steroidogenic enzymes. The PS particles were found to not affect these areas. However, when they measured hormone levels, they noticed that one hormone key in pregnancy (17-alpha-estradiol) was slightly lower (by 17%) after exposure to the smallest particles (50 nm).
In conclusion, the research found that PS-MNPs can enter and pass through an in vitro placenta model, but they caused only minor effects under the test conditions. Still, the fact that these particles were taken up by cells and slightly reduced hormone levels suggests that more research is needed, especially to understand the particles’ possible impact on hormone production during pregnancy.
Reference
Van Boxel, J. et al. (2025) “Limited passage and functional effects of polystyrene micro- and nanoplastics in a physiologically-relevant in vitro human placental co-culture model.” Reproductive Toxicity. DOI: 10.1016/j.reprotox.2025.108956
